To Make Reproduction Train Whistles, The Old Ways Are Best

Late last year, artist [Steve Messam]’s project “Whistle” involved 16 steam engine whistles around Newcastle that would fire at different parts of the day over three months. The goal of the project was bring back the distinctive sound of the train whistles which used to be fixture of daily life, and to do so as authentically as possible. [Steve] has shared details on the construction and testing of the whistles, which as it turns out was a far more complex task than one might expect. The installation made use of modern technology like Raspberry Pi and cellular data networks, but when it came to manufacturing the whistles themselves the tried and true ways were best: casting in brass before machining on a lathe to finish.

The original whistles are a peek into a different era. The bell type whistle has three major components: a large bell at the top, a cup at the base, and a central column through which steam is piped. These whistles were usually made by apprentices, as they required a range of engineering and manufacturing skills to produce correctly, but were not themselves a critical mechanical component.

In the original whistle shown here, pressurized steam comes out from within the bottom cup and exits through the thin gap (barely visible in the image, it’s very narrow) between the cup and the flat shelf-like section of the central column. That ring-shaped column of air is split by the lip of the bell above it, and the sound is created. When it comes to getting the right performance, everything matters. The pressure of the air, the size of the gap, the sharpness of the bell’s lip, the spacing between the bell and the cup, and the shape of the bell itself all play a role. As a result, while the basic design and operation of the whistles were well-understood, there was a lot of work to be done to reproduce whistles that not only operated reliably in all types of weather using compressed air instead of steam, but did so while still producing an authentic re-creation of the original sound. As [Steve] points out, “with any project that’s not been done before, you really can’t do too much testing.”

Embedded below is one such test. It’s slow-motion footage of what happens when the whistle fires after filling with rainwater. You may want to turn your speakers down for this one: locomotive whistles really were not known for their lack of volume.

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Lathe’s Tool Holder Holds a Rotary Tool

What is better than a tool? Two. What is better than two? Two tools tooling together. [tintek33] wanted a rotary tool to become an attachment on his mini lathe, the video is also below the break. Fortunately, Dremels and Proxxons are built to receive accessories, or in this case, become one. Even if the exact measurements do not apply to your specific hardware, we get to see the meat of the procedure from concept to use.

We start with where the rotary tool should be and get an idea of what type of bracket will be necessary. The design phase examines the important dimensions with a sketch and then a CAD mock-up. Suitably thick material is selected, and the steps for pulling the tool from the raw stock are shown with enough detail to replicate everything yet there is no wasted time in this video. That is important if you are making a quick decision as to whether or not this is worth your hard work. Once the brace is fully functional and tested, it is anodized for the “summer ocean” blue color to make it easy to spot in the tool heap. Some complex cuts are made and shown close-up.

Thank you [jafinch78] for your comment on Take a Mini Lathe for a Spin and check out [tintek33] using his mini lathe to make a hydraulic cylinder for an RC snow plow.

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Strobe For Wood Turning Makes Inspection Easy

The lathe is a simple enough tool to understand, but requires much practice to truly master. During the turning process, it’s often necessary to inspect the workpiece. This generally necessitates stopping the lathe, waiting for everything to spin down, and then starting again. This can be a major time sink when added up across the full scope of a project. However, the magic of strobes can help.

The basics of [Darcy]’s project will be familiar to any hacker who has worked with rotating machinery before. The rotational speed of the lathe is measured, in this case using a reed switch and a magnet. This signal is fed to a microcontroller, which controls the strobing of an LED lamp. By synchronizing the flashes to the speed of the lathe, it’s possible to view the workpiece as if it were standing still. By adjusting the offset of the flashes to the position of the lathe, it’s also possible to rotate this view to see the entire workpiece – all while the lathe remains spinning.

Further photos and videos are available in the Reddit thread. [Darcy] reports that despite his best efforts, he couldn’t quite find a business case for producing the hardware commercially, but the idea was too useful to leave languishing in a notebook. We’d love to hear your ideas on how this could improve turning projects, so be sure to let us know in the comments. If you’re just getting started with turning, it might be worth cutting a test bar to make sure your rig is up to snuff.

Take a Mini Lathe for a Spin

[This Old Tony] is no stranger to quality tools, but he started on a mini lathe. Nostalgia does not stop him from broadcasting his usual brand of snark (actually, it is doubtful that anything short of YouTube going offline will stop that). He rates the lathe’s ability to machine different materials and lets you decide if this is an investment, or a money pit.

Lathe parts range from a chintzy start/stop button assembly that looks like it would be at home on a Power Wheels restoration project to a convenient cam locking mechanism on the tail stock which is an improvement on the lathe with which our narrator learned. We see the speed tested and promptly disproved as marketing hoopla unless you allow for a 40% margin of error. It uses a 500 watt DC motor, so don’t try correcting for mains power frequency differences. The verdict on the lead screw and thread dial is that you get what you pay for and this is demonstrated by painstakingly cutting threads into aluminum. Finally, we see torture tests on cold rolled steel.

Maybe someone from the mini lathe community will stop by with their two-cents. If you appreciate this introduction to lathes, consider [This Old Tony]’s guide to CNC machines or injection molding. But for us, [Quinn Dunki’s] series of machine tools has been a real treat this year.

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Already Impressive CNC Router Gets An Extra Axis

The type of CNC machine within the financial reach of most DIYers is generally a three-axis affair, with a modest work envelope and a spindle that never quite seems powerful enough. That’s not to say that we don’t covet such a machine for our own shop of course, but comparing small machines with the “big boy” five-axis tools might leave the home-gamer feeling a tad inadequate.

Luckily, there’s a fix that won’t necessarily break the bank: adding a fourth axis to your CNC router. [This Old Tony] tore into his CNC router – a build we’ve featured before and greatly admire – to add a machine spindle that lets him work with the machine much as if it was a CNC lathe. The first video below covers the mechanical part of the build, which involves welding and machining a sturdy assembly to hold a spindle connecting a four-jaw chuck to a Lexium MDrive, a stepper motor with integrated driver and feedback that makes it act more like a servo. [Old Tony] covered integrating the drive into Mach4 in a previous video.

The assembled machine spindle is a beefy looking affair that can smoothly ramp up to 3000 rpm and has decent enough holding torque to allow it to act as an indexing head in addition to a lathe. The second video below shows some tests turning aluminum and steel; we were surprised by how aggressive the cuts can be before stalling the spindle.

No, it’s not a Tormach or Haas or even a Pocket NC, but it’s a great addition to an already capable machine, and we’re looking forward to what [Old Tony] cranks out with it.

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The Machinists’ Mantra: Precision, Thy Name Is Rigidity

“Everything is a spring”. You’ve probably heard that expression before. How deep do you think your appreciation of that particular turn of phrase really is? You know who truly, viscerally groks this? Machinists.

As I’ve blathered on about at length previously, machine tools are all about precision. That’s easy to say, but where does precision really come from? In a word, rigidity. Machine tools do a seemingly magical thing. They remove quantities of steel (or other materials medieval humans would have killed for) with a slightly tougher piece of steel. The way they manage to do this is by applying the cutting tool to the material within a setup that is so rigid that the material has no choice but to yield. Furthermore, this cutting action is extremely precise because the tool moves as little as possible while doing so. It all comes down to rigidity. Let’s look at a basic turning setup.

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The How and Why of Tungsten Carbide Inserts, and a Factory Tour

It seems a touch ironic that one of the main consumables in the machining industry is made out of one of the hardest, toughest substances there is. But such is the case for tungsten carbide inserts, the flecks of material that form the business end of most of the tools used to shape metal. And thanks to one of the biggest suppliers of inserts, Sweden’s Sandvik Coromant, we get this fascinating peek at how they’re manufactured.

For anyone into machining, the video below is a must see. For those not in the know, tungsten carbide inserts are the replaceable bits that form the cutting edges of almost every tool used to shape metal. The video shows how powdered tungsten carbide is mixed with other materials and pressed into complex shapes by a metal injection molding process, similar to the one used to make gears that we described recently. The inserts are then sintered in a furnace to bind the metal particles together into a cohesive, strong part. After exhaustive quality inspections, the inserts are ground to their final shape before being shipped. It’s fascinating stuff.

Coincidentally, [John] at NYC CNC just released his own video from his recent jealousy-inducing tour of the Sandvik factory. That video is also well worth watching, especially if you even have a passing interest in automation. The degree to which the plant is automated is staggering – from autonomous forklifts to massive CNC work cells that require no operators, this looks like the very picture of the factory of the future. It rolls some of the Sandvik video in, but the behind-the-scenes stuff is great.

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